This invention relates to stringed musical instruments of the type that may be selectively played in the fretted and unfretted mode, and more particularly to means for converting such an instrument from one mode to the other without affecting the playing xe2x80x9cactionxe2x80x9d of the instrument in terms of the distance each string must travel when pressed down to obtain the tuned pitch of a note in either the fretted or unfretted mode.
A stringed musical instrument is one having a substantially flat sound box across which strings are strung and a long neck connecting the box to a tuning head where pegs are mounted for tuning the individual strings. The strings pass either over a sound opening on the front of the box or between a pair of sound openings, for example, or simply pass over a sound transducer at or near the surface of the box in the case of an electronic instrument, such as an electronic guitar. The instrument is played by strumming or plucking the strings with one hand while selecting the pitch of a musical note to be made by the strings engaged with the other hand by pressing them down at selected positions along a fingerboard on the neck, normally with only the fingers, hence the term xe2x80x9cfingerboard.xe2x80x9d
In the case of a fretless instrument, the fingers press the selected strings against the fingerboard at locations that will then cause the strings to produce desired notes, each with a desired pitch, but in the case of a fretted instrument, the fingers press the strings against selected lateral bars or frets spaced longitudinally along the fingerboard. In that case, a pressed string produces a tone of a well defined pitch. In other words, frets influence the tonal character of the pitch to be very sharp and clearly defined, whereas the tonal character of the pitch produced on a fretless fingerboard is softer and less defined, thus producing a more swelling type of sound. This is so because the point of pressing the string against the fingerboard is not so well defined as in the case of pressing the string against a fret, the top of which is fixed to be above the surface of the fingerboard.
It is customary to use one or the other of the fretted and fretless types of instruments according to the nature of the music to be played, but sometimes it is desirable to switch from one type of instrument to the other on the same instrument in the middle of the piece of music being played. Consequently, it would be desirable to have both options available in one instrument by providing some means for effectively removing the frets quickly at the option of the musician, such as by switching a lever at the instrument head from one position to another, as shown in U.S. Pat. No. 5,325,757. That theoretically makes it possible for playing the instrument alternately in the two modes, fretted and fretless. However, once the instrument strings are tuned in the fretted mode (while the tonal characteristic of the instrument is very sharp and clearly defined), that prior-art instrument responds well only while being played in the fretted mode.
While playing that prior-art instrument in the unfretted mode, i.e., with the frets retracted into the neck, the distance the strings must travel increases when pressed down to obtain desired notes. As a result, the musician will find it more difficult to press the strings in the unfretted mode in order to play desired notes. Furthermore, the musician will find that the pitch of the notes produced in the unfretted mode increases from the tuned pitch produced by the same finger position used while playing the instrument in the fretted mode. In addition, the musician will need to adjust the position of the fingers to compensate for the increase/decrease in pitch of the notes when switching between the two modes. The result is that the musician is presented with an insurmountable xe2x80x9cactionxe2x80x9d problem.
An object of this invention is to provide a fretted/fretless string instrument without this xe2x80x9cactionxe2x80x9d problem so that the instrument will allow switching between its two modes while playing the same piece of music.
In accordance with the present invention, a fretted/fretless string instrument is provided with means for switching between its fretted and unfretted modes by rigidly securing the frets in the neck of the instrument with the frets protruding through spaced slots in a separate fingerboard between the strings and the neck. That separate fingerboard, provided with flanges extending over the sides of the neck, is implemented as a rigid board having a slightly curved surface between its flanges as is customary for string instruments, and is supported over the neck by two rails, one over each flange, having inwardly protruding pins that fit into spaced slide slots in the flanges. The rails are in turn supported on the neck by spaced screws that pass through horizontal slots in the rails and vertical slots in the flanges. The horizontal screw slots in the rails allow the rails to be driven back and forth relative to the neck while the vertical screw slots in the fingerboard flanges restrain the fingerboard to movement up and down relative to the neck as the rail pins protruding inwardly into the slide slots are driven back and forth between end portions of the slide slots oriented parallel to the neck and a sloped portion between the parallel and offset end portions. The extent that the parallel end portions are offset from each other in a vertical direction with respect to the neck determines the limits of up and down movement up to a position flush with the tops of the frets for the fretted mode down to a position preferably near the neck with a predetermined space between the neck and fingerboard. The advantage of this arrangement of raising a separate fingerboard up, vis-a-vis the prior art arrangement of lowering the frets in a fingerboard integral with the neck, is that the distance the strings must travel while playing the tuned instrument in the fretless mode remains the same for the same notes with the same pitch as when the fingerboard is lowered for playing in the fretted mode, thereby avoiding the xe2x80x9cactionxe2x80x9d problem of the aforesaid prior-art instrument noted above.
Thus, the separate fingerboard is provided with slots through which the frets protrude upwardly toward the strings for playing in the fretted mode while the separate fingerboard is in its lowered position, preferably a minimum space away from the neck. For the fretless mode, the separate fingerboard is raised so that it is even with the tops of the frets. This second position of the separate fingerboard flush with the tops of the frets provides a fretless fingerboard with a play action indistinguishable from a fretted fingerboard, thereby allowing the musician to play the instrument without an xe2x80x9cactionxe2x80x9d problem.
The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in connection with the accompanying drawings.